Argentina - 50 Wales - 44: Argentina wing Lucas Borges scored two tries within 30 seconds of each other at the beginning of the second half to spark a six-try blitz against visitors Wales in Tucuman on Saturday.
Pumas outhalf Felipe Contepomi added a try four minutes later to add to his four penalties and four conversions for a tally of 25 points.
Wales, under new coach Mike Ruddock, were disjointed and error-prone but managed five second-half tries themselves through Dwayne Peel, Jason Forster, Colin Charvis, Sonny Parker and Hal Luscombe.
Centre Gavin Henson added three penalties and five conversions in the match that turned into farce in the last 10 minutes.
The Pumas had the better of scrappy first half courtesy of a try to captain Gonazlo Longo while Wales counterpart Charvis was in the sinbin.
Instead of shooting for goal from the handy position, Argentina took a quick tap and Longo crashed over in the tackle of outhalf Ceri Sweeney and seemed to be held up. But the number eight, standing in as captain for Agustin Pichot, managed to twist in the tackle and ground the ball.
Contepomi added the conversion and his fourth penalty deep into injury-time to give the Pumas a 19-9 lead at the break after Henson had slotted three penalties for the visitors.
The second half was barely 30 seconds old when Borges pounced on a turnover to score his first try. Wales again threw a loose pass and Borges scooted away untouched for 40 metres to put the Pumas 31-9 ahead.
Felipe Contepomi then ran just past the tired-looking Wales pack still bound together from a scrum to score his side's third try.
Peel then scored Wales's first try by dancing through a poor defence from a quick tap, before Pumas centre Martin Gaitan touched down after a well-worked backline move in the 55th minute.
The game lost all semblance of pattern before Welsh debutant flanker Forster capped a sweeping move in the corner in the 64th minute.
Two minutes later centre Manuel Contepomi crashed over under the posts, and his brother's easy conversion made it 50 points.
Wales scored further tries through Charvis, Parker and Luscombe. The second and final Test is in Buenos Aires on Saturday.
ARGENTINA: H Senillosa; L Borges, M Gaitan, M Contepomi, J Piossek; F Contepomi, M Albina; R Roncero, F Mendez, O Hasan, P Albacete, I Lobbe, M Durand, L Ostiglia, G Longo (capt). Replacements: E Guinazu, P Cardinali, P Bouza, M Shusterman, L Fleming, G Bustos, J Orengo.
WALES: R Williams; H Luscombe, S Parker, G Henson, S Williams; C Sweeney, D Peel; D Jones, D Davies, A Jones, B Cockbain, G Llewellyn, C Charvis, J Forster, M Owen. Sin Bin: Charvis (31). Replacements: H Bennett, G Jenkins, D Morris, J Thomas, M Phillips, N Robinson, T Shanklin .
Referee: D Courtney (Irl).
